Temporal And Spatial Variation Of Drought In Beijing-Tianjin-Hebei And Its Response To Meteorological Factors

Agricultural drought is one of the important natural disasters facing mankind.Frequent agricultural droughts have brought huge threats to agricultural production and socio-economics in various countries,especially in the Beijing-Tianjin-Hebei region,where water resources are extremely scarce in China,has been plagued by agricultural drought for many years.Therefore,systematically studying the occurrence of drought events in the Beijing-Tianjin-Hebei region and accurately assessing them are of great significance to the regulation of regional water resources supply and demand and the prevention and reduction of drought.Based on the remote sensing data and meteorological data to retrieve the four drought indices of SPEI,SPI,TVDI and VSWI,this paper analyzes the drought situation in Beijing-Tianjin-Hebei region from 2000 to 2016,and the systematic analysis of the spatiotemporal changes of drought and the applicability of the four types of drought indices were conducted.The response relationship between TVDI and VSWI to changes in precipitation and temperature was analyzed and studied,with a view to providing technical and data support for regional drought control.The specific conclusions are as follows:1.The SPEI and SPI values at the January and March scales can reflect short-term drought changes,the SPEI and SPI values at the December scale can study interannual drought changes,and have better monitoring of lower soil moisture and river runoff.2.On the whole,the drought indices on multiple time scales can better reflect the extent of drought occurrence in the Beijing-Tianjin-Hebei region.No matter from the annual or seasonal scales,the four drought indexes show the progress of drought over time a gradual mitigation trend.The trends of SPI and SPEI are similar.The overall drought is mainly light drought,and the drought is mainly concentrated in the south.The drought frequency monitored by TVDI and VSWI is higher than that of SPEI and SPI.VSWI drought frequency is lower than TVDI.The TVDI and VSWI inversion results show that the Beijing-Tianjin-Hebei region has a higher degree of drought and a higher frequency in the winter and spring.The correlations between the four drought indices and soil relative humidity are as follows:SPEI>SPI>VSWI>TVDI.3.The systematic comparison and analysis of the meteorological factors on the hysteresis of drought.Correlation analysis shows that TVDI has a significant negative correlation with the first 0?1 month of precipitation and the first 0?2 months of temperature.The correlation between TVDI and precipitation and temperature in the first month is higher than in other months.VSWI showed significant positive correlation with the first 0?2 months precipitation and the first 0?3 months temperature.The correlation between VSWI and precipitation and temperature in the first month was higher than that in other months.VSWI and TVDI showed significant correlations with the current seasonal precipitation and current seasonal temperature.All showed significant correlations.TVDI and VSWI did not reach the significance test at the significance level of 0.1 and 0?1 year precipitation and 0?1 year temperature.Monthly and seasonal scales of VSWI and TVDI respond to changes in temperature over a longer duration than precipitation,while annual scales of VSWI and TVDI respond to changes in precipitation and temperature lower.